Aerosol containers for containing and dispensing of fluid materials are well known and widely used. Products sold in aerosol containers include, for example, foods such as whipped cream, toiletries such as shaving cream, deodorant and hair spray, and paints just to name a few. Dispensing is accomplished with the aid of propellant under pressure. Aerosol containers offer the advantage of convenience and nearly complete dispensing of the fluid product material from the container. Disadvantages of aerosol containers include limited operating temperature range, the fact that the container must be held upright to dispense properly, and increasingly, the environmental unacceptability of some of the most widely used propellants.
One of the principal classes of propellants are the fluorocarbons and chlorofluorocarbons (CFCs). The harmful effect of these materials on the ozone layer of the upper atmosphere has prompted a search for replacement. In fact, some major manufacturers of these materials have pledged to phase out their production over the next decade or so. Another class of propellants are hydrocarbons, particularly the liquified petroleum gas (LPG) hydrocarbons such as butane and pentane. While these do not tend to deplete the ozone layer (as far as is known), they do present other hazards because of their flammability.
Aerosol containers or cans fall into one of two categories as follows: (1) a standard aerosol container, wherein the product and propellant mix and (2) a barrier pack, wherein the product and the propellant are kept separated. The barrier type of aerosol container utilizes a radially expandable liner of flexible material as the barrier between material to be dispensed (which is inside the liner) and the propellant (which surrounds the liner). A representative liner of the barrier pack type is shown and described in U.S. Pat. No. 3,731,854 to Casey. One of the concerns that exists with the barrier pack container is that propellant is locked into the container after the product has been expelled, creating a hazard upon incineration of the container.
Self-pressurized containers have been suggested as an alternative to aerosol containers. Representative self-pressurized containers include those shown and described in U.S. Pat. Nos. 4,387,833 to Venus, Jr. and 4,423,829 to Katz. These references, which are rather similar in their teachings, describe apparatus for containing and dispensing of fluids under pressure in which no propellant is used and in which the fluid material to be dispensed is contained in a flexible plastic liner, which in turn is contained in (from the inside out) a fabric sleeve and an elastomeric sleeve, which surround the liner except for a small neck portion at the top. The liner, except for the neck portion and the closed bottom end, has a plurality of longitudinally extending depressions and ridges in alternating sequence so the liner in horizontal cross-section has a star like pattern. The liner wall configuration, from one depression to the next, comprises two parallel wall portions joined together by a semicircular ridge, as shown in FIG. 6 of the Katz '829 patent and FIG. 9 of the Venus patent. Both patentees disclose that the flexible liner is formed (e.g., by blow molding) in a smooth, essentially cylindrical configuration after which the folds or creases are formed. When the liner is filled under pressure with the desired product, the entire assembly expands radially. The elastomeric sleeve stores energy as a result of its radial expansion. This stored energy in the sleeve causes fluid to be dispensed upon opening of the dispensing valve. The container assembly contracts radially and the liner becomes folded, as it is emptied. Since the preferred plastic materials have memory, the liner seeks to return to the shape in which it is formed and resists becoming completely folded, which is essential to substantially complete expulsion of the product.
U.S. Pat. No. 4,964,540 to Katz discloses a liner of generally cylindrical shape, comprising a neck portion and a pleated portion which extends from the bottom of the neck portion to the closed bottom end of the liner. This pleated portion comprises a plurality of longitudinal or axial pleats characterized by alternating crests and troughs or valleys. A thin, resilient coating, of rubber-like latex material, is applied to the exterior surface of the liner and forms beads or ribs which fill the bottoms of the pleat valleys. According to patentee these ribs or valleys force the liner to regain its pleated shape in a smooth, orderly fashion as the fluid material is dispensed. Also, the latex coating has a relatively non-slip surface so that frictional forces develop between the liner and the elastomeric energy tube or sleeve which surrounds its, preventing axial slippage. This also makes more difficult the task of inserting the liner into an elastomeric sleeve during assembly.
Japanese published patent application publication number 63-294378, published Dec. 1, 1988, illustrates another liner for a dispensing container. The cross-sectional shape of the liner is generally similar to the cross-sectional shape of the liner shown in the Katz '829 and Venus patents.